Like mentioned above, it really does depend on what you’re into.
Starting in the Boston area, if you have time, take a ride up north to visit Gloucester. It’s a beautiful drive and great scenery.
We have usually stayed in Kennebunkport. They have a very walkable downtown with great places to eat. Take a drive down Ocean Ave to see Walkers Point. It is owned by the Bush Family and Jeb, just built a house here. You can see the house where President Bush and Barbara used to live as well.
Skip the crowds and downtown of Ogunquit, but stop by Perkins Cove and walk the Marginal Way. It’s a short, but beautiful walkway right on the ocean.
If you don’t have time on the ride to Portland, this would make a nice day trip, backtracking to some of these coastal towns.
In Boothbay Harbor, I would recommend the Coastal Maine Botanical Gardens. These are beautiful anytime of the year.
With that much time in Portland, I would definitely suggest getting out onto the water. Casco Bay, off of Portland, has literally hundreds of islands. Either by schooner, Ferry, Lobster boat or kayak, it’s definitely worth exploring. Whale cruises are fun as well if you never did one.
Bar Harbor and Arcadia should be on top of anyones list.
Part of the beauty of NE and Maine is just the natural beauty of the land. Whether you like, lighthouses, covered bridges, wineries, lobster, history, fairs, shopping, make a tour that fits your likes and enjoy.
While this may not have been what you were specifically asking, hopefully it brings up some ideas as to what to do.
